The present invention relates, in general, to document identification. More specifically, the present invention relates to an apparatus and method for discriminating among a plurality of document types such as currency bills of different denominations and/or from different countries and authenticating the genuineness of the same.
Machines that are currently available for simultaneous scanning and counting of documents such as paper currency are relatively complex and costly, and relatively large in size. The complexity of such machines can also lead to excessive service and maintenance requirements. These drawbacks have inhibited more widespread use of such machines, particularly in banks and other financial institutions where space is limited in areas where the machines are most needed, such as teller areas. The above drawbacks are particularly difficult to overcome in machines which offer much-needed features such as the ability to scan bills regardless of their orientation relative to the machine or to each other, and the ability to authenticate genuineness and/or denomination of the bills.
A variety of techniques and apparatus have been used to satisfy the requirements of automated currency handling systems. At the lower end of sophistication in this area of technology are systems capable of handling only a specific type of currency, such as a specific dollar denomination, while rejecting all other currency types. At the upper end are complex systems which are capable of identifying and discriminating among and automatically counting multiple currency denominations.
Currency discrimination systems typically employ either magnetic sensing or optical sensing for discriminating among different currency denominations. Magnetic sensing is based on detecting the presence or absence of magnetic ink in portions of the printed indicia on the currency by using magnetic sensors, usually ferrite core-based sensors, and using the detected magnetic signals, after undergoing analog or digital processing, as the basis for currency discrimination. A variety of currency characteristics can be measured using magnetic sensing. These include detection of patterns of changes in magnetic flux, patterns of vertical grid lines in the portrait area of bills, the presence of a security thread, total amount of magnetizable material of a bill, patterns from sensing the strength of magnetic fields along a bill, and other patterns and counts from scanning different portions of the bill such as the area in which the denomination is written out.
The more commonly used optical sensing techniques, on the other hand, are based on detecting and analyzing variations in light reflectance or transmissivity characteristics occurring when a currency bill is illuminated and scanned by a strip of focused light. The subsequent currency discrimination is based on the comparison of sensed optical characteristics with prestored parameters for different currency denominations, while accounting for adequate tolerances reflecting differences among individual bills of a given denomination. A variety of currency characteristics can be measured using optical sensing. These include detection of a bill""s density, color, length and thickness, the presence of a security thread and holes, and other patterns of reflectance and transmission. Color detection techniques may employ color filters, colored lamps, and/or dichroic beamsplitters.
In addition to magnetic and optical sensing, other techniques of detecting characteristic information of currency include electrical conductivity sensing, capacitive sensing (such as for watermarks, security threads, thickness, and various dielectric properties) and mechanical sensing (such as for size, limpness, and thickness).
A major obstacle in implementing automated currency discrimination systems is obtaining an optimum compromise between the criteria used to adequately define the characteristic pattern for a particular currency denomination, the time required to analyze test data and compare it to predefined parameters in order to identify the currency bill under scrutiny, and the rate at which successive currency bills may be mechanically fed through and scanned. Even with the use of microprocessors for processing the test data resulting from the scanning of a bill, a finite amount of time is required for acquiring samples and for the process of comparing the test data to stored parameters to identify the denomination of the bill.
Some of the currency scanning systems today scan for two or more characteristics of bills to discriminate among various denominations or to authenticate their genuineness. However, these systems do not efficiently utilize the information which is obtained. Rather, these systems generally conduct comparison based on the two or more characteristics independently of each other. As a result, the time required to make these comparisons is increased which in turn can reduce the operating speed of the entire scanning system.
Recent currency discriminating systems rely on comparisons between a scanned pattern obtained from a subject bill and sets of stored master patterns for the various denominations among which the system is designed to discriminate. As a result, the master patterns which are stored play an important role in a discrimination system""s ability to discriminate among bills of various denominations as well as between genuine bills and counterfeit bills. These master patterns have been generated by scanning bills of various denominations known to be genuine and storing the resulting patterns. However, a pattern generated by scanning a genuine bill of a given denomination can vary depending upon a number of factors such as the condition of the bill, e.g., whether it is a crisp bill in new condition or a worn, flimsy bill, as well as year in which the bill was printed, e.g., before or after security threads were incorporated into bills of some denominations. Likewise, it has been found that bills which have experienced a high degree of usage may shrink, resulting in a reduction of the dimensions of such bills. Such shrinkage may likewise result in variations in scanning patterns. As a result, if, for example, a $20 master pattern is generated by scanning a crisp, genuine $20 bill, the discrimination system may reject an unacceptable number of genuine but worn $20 bills. Likewise, if a $20 master pattern is generated using a very worn, genuine $20 bill, the discrimination system may reject an unacceptable number of genuine but crisp $20 bills.
It has been found that scanning U.S. bills of different denominations along a central portion thereof provides scanning patterns sufficiently divergent to enable accurate discrimination between different denominations. Such a discrimination device is disclosed in U.S. Pat. No. 5,295,196. However, currencies of other countries can differ from U.S. currency and from each other in a number of ways. For example, while all denominations of U.S. currencies are the same size, in many other countries currencies vary in size by denomination. Furthermore, there is a wide variety of bill sizes among different countries. In addition to size, the color of currency can vary by country and by denomination. Likewise, many other characteristics may vary between bills from different countries and of different denominations.
As a result of the wide variety of currencies used throughout the world, a discrimination system designed to handle bills of one country generally can not handle bills from another country. Likewise, the method of discriminating bills of different denominations of one country may not be appropriate for use in discriminating bills of different denominations of another country. For example, scanning for a given characteristic pattern along a certain portion of bills of one country, such as optical reflectance about the central portion of U.S. bills, may not provide optimal discrimination properties for bills of another country, such as German marks.
Furthermore, there is a distinct need for an identification system which is capable of accepting bills of a number of currency systems, that is, a system capable of accepting a number of bill-types. For example, a bank in Europe may need to process on a regular basis French, British, German, Dutch, etc. currency, each having a number of different denomination values.
Some of the optical scanning systems available today employ two optical scanheads disposed on opposite sides of a bill transport path. One of the optical scanheads scans one surface (e.g., green surface) of a currency bill to obtain a first set of reflectance data samples, while the other optical scanhead scans the opposite surface (e.g., black surface) of the currency bill to obtain a second set of reflectance data samples. These two sets of data samples are then processed and compared to stored characteristic patterns corresponding to the green surfaces of currency bills of different denominations. If degree of correlation between either set of data samples and any of the stored characteristic patterns is greater than a predetermined threshold, then the denomination of the bill is positively identified.
A drawback of the foregoing technique for scanning both surfaces of a currency bill is that it is time-consuming to process and compare both sets of data samples for the scanned bill to the stored characteristic patterns. The set of data samples corresponding to the black surface of the scanned bill are processed and compared to the stored characteristic patterns even though no match should be found. As previously stated, the stored characteristic patterns correspond to the green surfaces of currency bills of different denominations.
Another drawback of the foregoing scanning technique is that the set of data samples corresponding to the black surface of the scanned bill occasionally leads to false positive identification of a scanned bill. The reason for this false positive identification is that if a scanned bill is slightly shifted in the lateral direction relative to the bill transport path, the set of data samples corresponding to the black surface of the scanned bill may sufficiently correlate with one of the stored characteristic patterns to cause a false positive identification of the bill. The degree of correlation between the set of xe2x80x9cblackxe2x80x9d data samples and the stored xe2x80x9cgreenxe2x80x9d characteristic patterns should, of course, not be greater than the predetermined threshold for positively identifying the denomination of the bill.
Furthermore, in currency discriminating systems that rely on comparisons between a scanned pattern obtained from a subject bill and sets of stored master patterns, the ability of a system to accurately line up the scanned patterns to the master patterns to which they are being compared is important to the ability of a discrimination system to discriminate among bills of various denominations as well as between genuine bills and counterfeit bills without rejecting an unacceptable number of genuine bills. However, the ability of a system to line up scanned and master patterns is often hampered by the improper initiation of the scanning process which results in the generation of scanned patterns. If the generation of scanned patterns is initiated too early or too late, the resulting pattern will not correlate well with the master pattern associated with the identity of the currency; and as a result, a genuine bill may be rejected. There are a number of reasons why a discrimination system may initiate the generation of a scanned pattern too early or too late, for example, stray marks on a bill, the bleeding through of printed indicia from one bill in a stack onto an adjacent bill, the misdetection of the beginning of the area of the printed indicia which is desired to be scanned, and the reliance on the detection of the edge of a bill as the trigger for the scanning process coupled with the variance, from bill to bill, of the location of printed indicia relative to the edge of a bill. Therefore, there is a need to overcome the problems associated with correlating scanned and master patterns.
In some currency discriminators bills are transported, one at a time, passed a discriminating unit. As the bills pass the discriminating unit, the denomination of each bill is determined and a running total of each particular currency denomination and/or of the total value of the bills that are processed is maintained. A number of discriminating techniques may be employed by the discriminating unit including optical or magnetic scanning of bills. A plurality of output bins are provided and the discriminator includes means for sorting bills into the plurality of bins. For example, a discriminator may be designed to recognize a number of different denominations of U.S. bills and comprise an equal number of output bins, one associated with each denomination. These discriminators also include a reject bin for receiving all bills which cannot be identified by the discriminating unit. These bills may later be examined by an operator and then either re-fed through the discriminator or set aside as unacceptable.
Depending on the design of a discriminator, bills may be transported and scanned either along their long dimension or their narrow dimension. For a discriminator that transport bills in their narrow dimension, it is possible that a given bill may be oriented either face up or face down and either top edge first (xe2x80x9cforwardxe2x80x9d direction) or top edge last (xe2x80x9creversexe2x80x9d direction). For discriminators that transport bills in their long dimension, it is possible that a given bill may be oriented either face up or face down and either left edge first (xe2x80x9cforwardxe2x80x9d direction) or left edge last (xe2x80x9creversexe2x80x9d direction). The manner in which a bill must be oriented as it passes a discriminating unit depends on the characteristics of the discriminator. Some discriminators are capable of identifying the denomination of a bill only if it is fed with a precise orientation, e.g., face up and top edge first. Other discriminators are capable of identifying bills provided they are xe2x80x9cfacedxe2x80x9d (i.e., fed with a predetermined face orientation, that is all face up or all face down). For example, such a discriminator may be able to identify a bill fed face up regardless of whether the top edge is fed first or last. Other discriminators are capable of identifying the denomination fed with any orientation. However, whether a given discriminator can discriminate between bills fed with different orientations depends on the discriminating method used. For example, a discriminator that discriminates bills based on patterns of transmitted light may be able to identify the denomination of a forward fed bill regardless of whether the bill is fed face up or face down, but the same discriminator would not be able to discriminate between a bill fed face up and a bill fed face down.
Currently, discriminators are known which discriminate and/or sort by denomination when bills are properly faced. In such systems, all reverse-faced bills are not identified and are routed to a reject receptacle. Also discriminators are known which discriminate and/or sort between all bills facing up and all bills facing down. For example, in a multi-output pocket system, all face up bills, regardless of denomination, may be routed to a first pocket and all face down bills, regardless of denomination, may be routed to a second pocket. Furthermore, there is currently known discriminators designed to accept a stack of faced bills and flag the detection of a reverse-faced bill, thus allowing the reverse-faced bill to be removed from the stack. However, there remains a need for a discriminator that can detect and flag the presence of a bill oriented with an incorrect forward/reverse orientation and a discriminator that can sort between forward-oriented bills and reverse-oriented bills.
Furthermore, for a number of reasons, a discriminating unit may be unable to determine the denomination of a bill. These reasons include a bill being excessively soiled, worn, or faded, a bill being torn or folded, a bill being oriented in a manner that the discriminating unit cannot handle, and the discriminating unit having poor discriminating performance. Furthermore, the discriminating unit and/or a separate authenticating unit may determine that a bill is not genuine. In current discriminators, such unidentified or non-genuine bills are deposited in a reject receptacle.
A characteristic of the above described discriminators is that the value of any rejected unidentified bills is not added to the running total of the aggregate value of the stack of bills nor do the counters keeping track of the number of each currency denomination reflect the rejected unidentified bills. While this is desirable with respect to bills which are positively identified as being fake, it may be undesirable with respect to bills which were not identified for other reasons even though they are genuine bills. While the bills in a reject receptacle may be re-fed through the discriminator, the operator must then add the totals from the first batch and the second batch together. Such a procedure can be inefficient in some situations. Also, if a bill was rejected the first time because it was, for example, excessively soiled or too worn, then it is likely that the bill will remain unidentified by the discriminating unit even if re-fed.
A problem with the above described situations where the totals and/or counts do not reflect all the genuine bills in a stack is that an operator must then count all the unidentified genuine bills by hand and add such bills to separately generated totals. As a result the chance for human error increases and operating efficiency decreases. Take for example a bank setting where a customer hands a teller a stack of currency to be deposited. The teller places the stack of bills in a discriminator, the display on the discriminator indicates that a total of $730 has been identified. However, fourteen genuine bills remain unidentified. As a result, the teller must count these fourteen bills by hand or re-fed through the discriminator and then add their total to the $730 total. An error could result from the teller miscounting the unidentified bills, the teller forgetting to add the two totals together, or the teller overlooking the unidentified bills entirely and only recording a deposit of $730. Moreover, even if the teller makes no mistakes, the efficiency of the teller is reduced by having to manually calculate additional totals. The decrease in efficiency is further aggravated where detailed records must be maintained about the specific number of each denomination processed during each transaction.
Therefore, there is a need for a currency discriminator which is capable of conveniently and efficiently accommodating genuine bills that, for whatever reason, remain unidentified after passing through the discriminating unit of a discriminator.
A number of methods have been developed for authenticating the genuineness of security documents. These methods include sensing magnetic, optical, conductive, and other characteristics of documents under test. In general, it has been found that no single authentication test is capable of detecting all types of counterfeit documents while at the same time not rejecting any genuine documents. Therefore, more than one test may be employed whereby a first test is used to detect certain types of counterfeits and additional tests are used to detect other types of counterfeits.
It has been known that the illumination of certain substances with ultraviolet light causes the substances to fluoresce, that is, to emit visible light. Some documents employ fluorescent materials as a security feature to inhibit counterfeiting. Typically, these fluorescent security features comprise a marking which is visibly revealed when the document is illuminated with ultraviolet light. Previous methods have been developed to authenticate such documents by sensing the fluorescent light emitted by a document illuminated by ultraviolet light and comparing the sensed fluorescent light to the fluorescent light emitted by genuine documents.
Conversely, some documents, such as U.S. currency, are manufactured from special paper designed not to fluoresce under ultraviolet light. Previously known authenticating methods for such documents have sensed for the emission of fluorescent light under ultraviolet illumination and have rejected as counterfeit those documents emitting fluorescent light.
However, it has been found that the presently known ultraviolet authentication methods do not detect all types of counterfeits. For example, while many counterfeit U.S. bills do emit fluorescent light under ultraviolet illumination, some counterfeit U.S. bills do not.
It is an object of the present invention to provide an improved method and apparatus for identifying documents.
It is an object of the present invention to provide an improved method and apparatus for identifying, authenticating, and counting currency bills comprising a plurality of currency denominations.
It is an object of the present invention to provide an improved method and apparatus for discriminating among documents of different types including currency documents of different denominations.
It is an object of the present invention to provide an improved method and apparatus for discriminating among currency bills comprising a plurality of currency denominations.
It is another object of this invention to provide-an improved method and apparatus of the above kind which is capable of efficiently discriminating among, authenticating, and counting bills of several currency denominations at a high speed and with a high degree of accuracy.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of efficiently discriminating currencies from a number of different countries.
It is another object of this invention to provide a currency evaluation device able to discriminate among different denominations of bills from two or more currency systems.
It is another object of this invention to provide a currency evaluation device able to discriminate among different denominations of both Canadian and German bills.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of scanning a document such as a currency bill along two or more laterally displaced segments to thereby identify the document.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of scanning a document along two or more laterally displaced segments by using two or more laterally displaced scanheads.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of scanning a document along two or more laterally displaced segments by using two or more laterally displaced sensors of a linear array scanhead.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of scanning a document along two or more laterally displaced segments by using one or more laterally moveable scanheads.
It is another object of this invention to provide an improved method and apparatus of the above kind wherein the above scanheads or sensors retrieve optical reflectance information from a document under test and use such reflectance information to determine the identity of the document.
It is another object of this invention to provide an improved method and apparatus of the above kind which identifies a document by comparing one or more scanned patterns generated by scanning a document under test with one or more scanheads or one or more sensors and comparing the scanned pattern or patterns with one or more master patterns associated with genuine documents.
It is another object of this invention to provide an improved method and apparatus of the above kind which identifies a document by determining the size of the document.
It is another object of this invention to provide an improved method and apparatus of the above kind which identifies a document by determining the color of the document.
It is another object of this invention to provide an improved method and apparatus of the above kind which identifies a document based on a combination of size information and scanned/master pattern comparison.
It is another object of this invention to provide an improved method and apparatus of the above kind which identifies a document based on a combination of color information and scanned/master pattern comparison.
It is another object of this invention to provide an improved method and apparatus of the above kind which identifies a document based on a combination of size information, color information, and scanned/master pattern comparison.
It is another object of this invention to provide an improved method and apparatus of the above kind in which only selected ones of a number of scanheads or sensors are activated to scan a document.
It is another object of this invention to provide an improved method and apparatus of the above kind in which scanned patterns are generated only from the output or data derived therefrom of selected ones of a number of scanheads or sensors which are activated to scan a document.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the selection of one or more of a number of scanheads or sensors to scan a document is based on size information.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the selection of one or more of a number of scanheads or sensors to scan a document is based on color information.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the lateral positioning of one or more moveable scanheads is based on size and/or color information detected from the document.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the selection of the output or data derived therefrom of one or more of a number of scanheads or sensors for the generation of scanned patterns is based on size information.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the selection of the output or data derived therefrom of one or more of a number of scanheads or sensors for the generation of scanned patterns is based on color information.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of scanning either side or both sides of a document.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the amount of information that must be processed is reduced by tailoring the areas from which scanned patterns are derived, such reduction being based on pre-scan information detected from a document such as the size and/or color of a document to be scanned.
It is another object of this invention to provide an improved method and apparatus of the above kind in which the amount of information that must be processed is reduced by tailoring the data which must be assembled into one or more scanned patterns, such reduction being based on information detected from a document during the scanning process itself, the information detected during the scanning process itself including, for example, size and/or color information.
It is another object of this invention to provide an improved method and apparatus of the above kind in which size and/or color information detected from a document is used to generate a preliminary set of potentially matching documents and in which one or more scanned patterns generated from a document are compared with master patterns chosen from the preliminary set.
It is another object of this invention to provide an improved method and apparatus of the above kind in which a document to be scanned is transported past one or more scanheads in a centered or justified manner along a transport path.
It is another object of this invention to provide an improved method and apparatus of the above kind in which a document to be scanned is transported past one or more scanheads along a transport path and in which one or more sensors separate from the one or more scanheads are used to determine the lateral positioning of the document within the transport path.
It is another object of this invention to provide an improved method and apparatus of the above kind in which a document to be scanned is transported past one or more scanheads along a transport path and in which the lateral positioning of the document within the transport path is determined by analyzing the output of one or more scanheads.
It is another object of this invention to provide an improved method and apparatus of the above kind in which a document to be scanned is transported past one or more scanheads along a transport path and in which the skew of the document is determined by analyzing of output of one or more scanheads or analyzing the output of one or more separate sensors.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of accepting documents fed either face up or face down.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of accepting documents fed in either the forward or reverse direction, i.e., top edge first or top edge last.
A related object of the present invention is to provide such an improved currency discrimination and counting apparatus which is compact, economical, and has uncomplicated construction and operation.
It is an object of the present invention to provide an improved currency scanning and counting machine which is relatively simple and compact, while at the same time providing a variety of advanced features which make the machine convenient and useful to the operator.
Another object of this invention is to provide such an improved currency scanning and counting machine that is relatively inexpensive to manufacture and maintain, and which also facilitates service and maintenance. In this connection, a related object of the invention is to provide such a machine having a relatively small number of parts, and in which most of the parts are arranged in a manner to have a long operating life with little or no maintenance.
It is a further object of this invention to provide such a machine that is capable of operating at a faster throughput rate than any previous machine able to determine the denomination of the scanned bills.
It is another object of the present invention to provide an improved method and apparatus for identifying a currency as belonging to a set of one or more currency bills.
It is another object of the present invention to provide an improved method and apparatus for determining the identity of a currency bill.
It is another object of the present invention to provide an improved method of generating modified scanned patterns.
It is another object of the present invention to provide an improved method of generating modified master patterns.
It is another object of the present invention to provide an improved method and apparatus for determining the identity of a currency bill by comparing a modified version of a scanned pattern with one or more master patterns.
It is another object of the present invention to provide an improved method and apparatus for determining the identity of a currency bill by comparing modified versions of one or more master patterns with a scanned pattern.
It is another object of the present invention to provide an improved method and apparatus using an improved pattern generation method for improving the ability of a discrimination system to accurately reject improper bills while reducing the likelihood of rejecting genuine bills.
It is another object of this invention to provide an improved document counting and discriminating apparatus that is capable of flagging unidentified bills.
It is another object of this invention to provide an improved document counting and discriminating apparatus that flags unidentified bills by suspending operation of the apparatus.
It is another object of this invention to provide an improved document counting and discriminating apparatus of the above type that can conveniently be caused to resume operation after an operator of the apparatus has examined an unidentified bill.
It is another object of this invention to provide an improved document counting and discriminating apparatus of the above type whereby the denomination or kind of any unidentified bill may be conveniently added to appropriate counters and the operation of the apparatus conveniently resumed when an operator determines that an unidentified bill is acceptable and whereby the operation of the apparatus may be conveniently resumed without adversely affecting any counter when an operator determines that an unidentified bill is not acceptable.
It is another object of this invention to provide an improved document counting and discriminating apparatus whereby the discriminator prompts the operator as to the identity of any flagged bills, such as by prompting the operator as to the denomination of any bill whose denomination has not been determined by the discriminator.
It is another object of this invention to provide an improved document discriminating apparatus that can flag a document based on the forward or reverse orientation of the document.
It is another object of this invention to provide an improved document discriminating apparatus that can sort between documents having a forward orientation and documents having a reverse orientation.
It is another object of the present invention to provide an improved method and apparatus for authenticating documents including currency documents.
It is another object of the present invention to provide an improved method and apparatus for authenticating United States currency bills.
It is another object of the present invention to provide an improved method and apparatus for authenticating documents which may be employed in a currency discriminating apparatus.
It is an object of the present invention to provide an improved method and apparatus for authenticating documents including currency documents by illuminating a document with ultraviolet light.
It is another object of the present invention to provide an improved method and apparatus for authenticating documents which improves the ability of a system to accurately reject improper documents while reducing the likelihood of rejecting genuine documents.
Other objects and advantages of the invention will become apparent upon reading the following detailed description in conjunction with the accompanying drawings.
In accordance with one embodiment of the present invention, the foregoing objectives are realized by providing a currency counting and discrimination device for receiving a stack of currency bills, rapidly counting and discriminating the bills in the stack, and then re-stacking the bills. This device includes an input receptacle for receiving a stack of currency bills to be discriminated, a discriminating unit for discriminating the currency bills by denomination, an output receptacle for receiving the currency bills after they have been discriminated, and a transport mechanism for transporting the currency bills, one at a time, from the input receptacle past the discriminating unit and to the output receptacle. The transport mechanism includes stripping wheels for stripping the lowermost bill from a stack of bills in the input receptacle, and a pair of driven transport rolls on opposite sides of the discriminating unit for transporting each bill past the discriminating unit. One of the transport rolls also receives bills directly from the stripping wheels and transports the received bills to the region between the pair of transport rolls.
In one embodiment, a pair of photosensors are located at opposite sides of the bill transport path, each photosensor including a light source and a protective lens on one side of the bill, and a photodetector and a protective lens on the other side of the bill. The lenses for both the light sources and the photodetectors are located sufficiently close to each other that the lenses are wiped by the bills transported therebetween.
In accordance with one embodiment of the present invention, the objectives enumerated above are achieved by scanning a document along one or more segments, generating one or more scanned patterns therefrom, and comparing the one or more scanned patterns to one or more master patterns associated with scans along corresponding segments of genuine documents. According to one embodiment, bills are fed in and scanned across their narrow dimension. According to another embodiment, bills are fed in and scanned across their wide dimension. One embodiment of the present invention involves a technique based on the optical sensing of reflectance characteristics obtained by illuminating and scanning a document such as a currency bill along an appropriately selected segment or segments of a document. Light reflected from the bill as it is optically scanned is detected and used as an analog representation of the variation in the dark and light content of the printed pattern or indicia on the bill surface.
A series of such detected reflectance signals are obtained by sampling and digitally processing, under microprocessor control, the reflected light at a plurality of predefined sample points as the bill is moved across the illuminated strip. Accordingly, a fixed number of reflectance samples is obtained across the note. The data samples obtained for a bill scan are subjected to digital processing, including a normalizing process to deaccentuate variations due to contrast fluctuations in the printed pattern or indicia existing on the surface of the bill being scanned. The normalized reflectance data represent a characteristic pattern that is fairly unique for a given bill identity and incorporates sufficient distinguishing features between characteristic patterns for different bill-types so as to accurately differentiate therebetween.
By using the above approach, a series of master characteristic patterns are generated and stored using standard bills for each denomination of currency that is to be detected. The xe2x80x9cstandardxe2x80x9d bills used to generate the master characteristic patterns are preferably bills that are slightly used bills. According to one embodiment, two or four characteristic patterns are generated and stored within system memory for each detectable bill-type. The stored patterns correspond, respectively, to optical scans performed on one or both sides of a bill along xe2x80x9cforwardxe2x80x9d and xe2x80x9creversexe2x80x9d directions relative to the pattern printed on the bill. For bills which produce significant pattern changes when shifted slightly to the left or right, such as the $10 bill in U.S. currency, it is preferred to store two patterns for each of the xe2x80x9cforwardxe2x80x9d and xe2x80x9creversexe2x80x9d directions, each pair of patterns for the same direction represent two scan areas that are slightly displaced from each other along the lateral dimension of the bill. The document identification system of this invention may be adapted to identify different denominations of a plurality of currency systems. Accordingly, a master set of different characteristic patterns is stored within the system memory for subsequent correlation purposes.
According to one embodiment a master pattern for a given denomination is generated by averaging a plurality of component patterns, typically three, each generated by scanning a genuine bill of the given denomination.
According to one method, a master pattern for a given denomination is generated by averaging a plurality of component patterns, wherein the component patterns are generated by scanning one or more genuine bills of xe2x80x9cstandardxe2x80x9d or average quality of the given denomination. A xe2x80x9cstandardxe2x80x9d bill is a slightly used bill, as opposed to a crisp new bill or one which has been subject to a high degree of usage.
According to another method, a master pattern for a given denomination is generated by averaging a plurality of component patterns, wherein some of the component patterns are generated by scanning one or more new bills of the given denomination and some of the component patterns are generated by scanning one or more old bills of the given denomination.
According to the correlation technique of this invention, the pattern generated by scanning a bill under test and processing the sampled data is compared with each of the prestored characteristic patterns within a preliminary set (to be described below) to generate, for each comparison, a correlation number representing the extent of similarity between corresponding ones of the plurality of data samples for the compared patterns. Bill identification is based on designating the scanned bill as belonging to the bill-type corresponding to the stored characteristic pattern for which the correlation number resulting from pattern comparison is determined to be the highest. The possibility of a scanned bill having its identity mischaracterized following the comparison of characteristic patterns is significantly reduced by defining a bi-level threshold of correlation that must be satisfied for a xe2x80x9cpositivexe2x80x9d call to be made.
In essence, the present invention utilizes an optical sensing and correlation technique for positively identifying any of a plurality of different bill-types regardless of whether the bill is scanned along the xe2x80x9cforwardxe2x80x9d or xe2x80x9creversexe2x80x9d directions. Likewise in one embodiment of the present invention, the system is capable of identifying any of a plurality of different bill-types regardless of whether the bill is fed into the system with a xe2x80x9cface upxe2x80x9d or xe2x80x9cface downxe2x80x9d orientation. Face orientation can be accommodated by storing master patterns scanned from both sides of genuine documents, using a system having one or more scanheads on a single side of a document transport path, and comparing scanned patterns to master patterns retrieved from both sides of genuine documents. Alternatively, scanheads may be placed on both sides of a document transport path, scanned patterns retrieved from respective sides can be compared to master patterns from both sides or master patterns from corresponding sides where face orientation can be determined. Additionally, a cross check can be performed so that the identity determined by a match of patterns from one side of a document is consistent with the identity indicated by comparing patterns from the other side of the document. For both one-sided and two-sided scanhead systems, where the face orientation of a document can be determined before patterns are compared, scanned patterns from one side of a document can be compared only to master patterns retrieved from a corresponding side. Similar methods can be employed for accommodating documents fed in forward and reverse directions.
In one embodiment, the invention is particularly adapted to be implemented with a system programmed to track each identified currency identity so as to conveniently present aggregate totals for bills that have been identified at the end of a scan run. One embodiment incorporates an abbreviated curved transport path for accepting currency bills that are to be counted and transporting the bills about their narrow dimension across a scanhead located downstream of the curved path and onto a conventional stacking station where sensed and counted bills are collected. In one embodiment, a scanhead of the present invention operates in conjunction with an optical encoder which is adapted to initiate the capture of a predefined number of reflectance data samples when a bill (and, thus, the indicia or pattern printed thereupon) moves across a coherent strip of light focused by the scanhead.
In one embodiment, a scanhead of the present invention uses a pair of light-emitting diodes (xe2x80x9cLEDsxe2x80x9d) to focus a coherent light strip of predefined dimensions and having a normalized distribution of light intensity across the illuminated area. The LEDs are angularly disposed and focus the desired strip of light onto the narrow dimension of a bill positioned flat across the scanning surface of the scanhead. A photodetector detects light reflected from the bill. The sampling of the photodetector output is controlled by the optical encoder to obtain the desired reflectance samples. In one embodiment, initiation of sampling is based upon detection of the edge of a bill. In another embodiment for bills having a borderline surrounding the remaining printed indicia, initiation of sampling is based upon detection of the borderline of a bill.
Some of the above described techniques and apparatus as tailored to scanning U.S. currency are more fully disclosed in U.S. Pat. No. 5,295,196, for a xe2x80x9cMethod and Apparatus for Currency Discrimination and Countingxe2x80x9d incorporated herein in its entirety.
In adapting the currency discriminating method and apparatus disclosed in U.S. Pat. No. 5,295,196 to optimize the scanning of currencies from countries other than the United States, it is first noted that while it has been found that scanning along the central portion of the green side of U.S. bills provides good patterns to discriminate between the different U.S. denominations, foreign bills may require scanning along segments located in locations other than the center and the desirable areas to scan bills can vary from bill-type to bill-type. For example, it may be determined that it is desirable to scan German marks in the forward direction along a segment 1 inch (2.54 cm) to the left of center along the top face of a bill while it may be desirable to scan British pounds along a segment 1.5 inches (3.81 cm) to the right of center. To provide a system capable of scanning along a plurality of laterally displaced segments, the present invention utilizes either a plurality of laterally displaced stationary scanheads, one or more laterally moveable scanheads, or a linear array scanhead having a plurality of laterally displaced sensors. In one embodiment, the scanheads or sensors are arranged in a symmetrical manner about the center of document to be scanned. Such a symmetrical arrangement aids in providing a system which is capable of accepting bills fed in both the forward and reverse directions.
Additionally, while all denominations of U.S. currency have the same size, currencies from other countries may vary in size from country to country as well as from denomination to denomination for currency from the same country. In one embodiment of the present invention, variance in size is accommodated by incorporating means for determining the size of a document. These size determining means may include sensors separate from the scanheads or scanning sensors discussed above or alternatively, in some embodiments of the present invention, may include the scanheads or scanning sensors discussed above which are used for the retrieval of scanned characteristic patterns. Based on the size information retrieved from a bill, selected scanheads may be activated, laterally moveable scanheads may be appropriately positioned and activated, and/or selected sensors in a linear array scanhead may be activated to permit scanning along appropriate segments of a bill based on its size. Alternatively, all scanheads or scanning sensors may be activated and the output of appropriately positioned scanheads or scanning sensors may be processed to generate scanned patterns based on the size of a bill. Furthermore, based on the size of a bill, a preliminary determination can be made as to which of a plurality of genuine bill-types a bill under test may potentially match. Based on such a preliminary determination, the comparison of generated scanned patterns can be limited to only master patterns associated with bill-types chosen from the preliminary set of potentially matching bills.
Likewise, the transport mechanism which transports documents to be scanned past the above described scanheads may be designed to transport documents in a centered manner, left or right justified manner, in a non-controlled lateral positioned manner, in a non-skewed manner, or in a skewed manner. Sensors separate and distinct from the above described scanheads or the above described scanheads themselves may be used to determine the lateral positioning of transported bills and/or their degree of skew. Based on a determination of the lateral positioning of a bill and/or its skew, appropriately positioned scanheads or scanning sensors may be activated or laterally moveable scanheads may be appropriately positioned and activated or the output from appropriately positioned scanheads or scanning sensors may be processed to generate scanned patterns based on the lateral positioning and/or skew of the bill.
Additionally, while all denominations of U.S. currency have the same colors (a xe2x80x9cgreenxe2x80x9d side and a xe2x80x9cblackxe2x80x9d side), currencies from other countries may vary in color from country to country as well as from denomination to denomination for currency from the same country. In one embodiment of the present invention, variance in color is accommodated by incorporating means for determining the color of a document. These color determining means may include sensors separate from the scanheads or sensors discussed above or alternatively, in some embodiments of the present invention, may include the appropriately modified scanheads or sensors discussed above which are used for the retrieval of scanned characteristic patterns. For example, colored filters may be placed in front of the above described scanheads or sensors. Based on the color information retrieved from a bill, selected scanheads may be activated, laterally moveable scanheads may be appropriately positioned and activated, and/or selected sensors in a linear array scanhead may be activated to permit scanning along appropriate segments of a bill based on its color. Alternatively, all scanheads or scanning sensors may be activated and the output of appropriately positioned scanheads or scanning sensors may be processed to generate scanned patterns based on the color of a bill. Furthermore, based on the color of a bill, a preliminary determination can be made as to which of a plurality of genuine bill-types a bill under test may potentially match. Based on such a preliminary determination, the comparison of generated scanned patterns can be limited to only master patterns associated with bill-types chosen from the preliminary set of potentially matching bills.
In one embodiment of the present invention, both color and size information may be utilized as described above.
In one embodiment of the present invention, scanheads are positioned on both sides of a document transport path so as to permit scanning of either or both sides of a document.
According to one embodiment, an apparatus for currency discrimination comprises first and second stationary scanheads, disposed on opposite sides of a bill transport path, for scanning respective first and second opposing surfaces of a bill traveling along the bill transport path and for producing respective output signals. The bill travels along the transport path in the direction of a predetermined dimension of the bill. A memory stores master characteristic patterns corresponding to associated predetermined surfaces (e.g., green surfaces) of a plurality of denominations of genuine bills. Sampling circuitry samples the output signals associated with the respective first and second opposing surfaces of the scanned bill. A signal processor is programmed to determine which one of the first and second opposing surfaces corresponds to the associated predetermined surfaces of the plurality of denominations of genuine bills. According to one embodiment adapted for discriminating, for example, U.S. bills, the determination as to which surface of a bill corresponds to a predetermined surface is made by detecting the borderlines on each side of a bill and determining the relative times of detection of each borderline. The processor then correlates the output signal associated with the one of the first and second opposing surfaces corresponding to the associated predetermined surfaces with the master characteristic patterns. If the degree of correlation between the selected output signal and any of the stored characteristic patterns is greater than a predetermined threshold, then the denomination of the bill is positively identified.
For each scanhead, initiation of sampling is based upon detection of the change in reflectance value that occurs when the outer border of the printed pattern on a bill is encountered relative to the reflectance value obtained at the edge of the bill where no printed pattern exists. According to one embodiment of this invention, illuminated strips of at least two different dimensions are used for the scanning process. A narrow strip is used initially to detect the starting point of the printed pattern on a bill and is adapted to distinguish the thin borderline that typically marks the starting point of and encloses the printed pattern on a bill. For the rest of the preselected dimension scanning following detection of the borderline of the printed pattern, a substantially wider strip of light is used to collect the predefined number of samples for a bill scan. The generation and storage of characteristic patterns using standard notes and the subsequent comparison and correlation procedure for classifying the scanned bill as belonging to one of several predefined currency denominations is based on the above-described sensing and correlation technique.
Furthermore, in accordance with another feature of the present invention, the objectives enumerated above in connection with correlating patterns are achieved by repetitively comparing a scanned pattern with multiple sets of master patterns until a sufficient match is found, or alternatively, by repetitively comparing a set of original master patterns with multiple scanned patterns until a sufficient match is found. The multiple sets of master patterns comprise an original set of master patterns plus one or more sets of modified versions of the original master patterns. The multiple scanned patterns comprise an original scanned pattern plus one or more modified versions of the original scanned patterns. Each modified pattern comprises one or more replicated data values from a corresponding original pattern to which each modified pattern is to be compared. Alternatively, each modified master pattern comprises one or more data values which are set equal to zero.
Briefly, in accordance with one embodiment, an improved method of generating modified scanned or master patterns for use in a discrimination system capable of identifying one or more currency bills is provided. Each of the scanned and master patterns comprises a sequence of data values representing analog variations of characteristic information along a segment of a bill and each pattern has a leading end and a trailing end. Each of the data values has an associated sequence position. The modified scanned or master patterns are generated by designating either the scanned pattern or the master pattern for modification and inserting a predetermined number, R, of data values at either the trailing end of the sequence of data values of the designated pattern when the modification is performed in the forward direction or the leading end of the sequence of data values of the designated pattern when the modification is performed in the backward direction. This modification effectively removes R data values from the leading or trailing end of the designated pattern. Either the last R data values of the designated pattern are set equal to the last R data values of the non-designated pattern when the modification is performed in the forward direction or the first R data values of the designated pattern are set equal to the first R data values of the non-designated pattern when the modification is performed in the backward direction. Alternatively, the modified master patterns are generated by inserting R data samples at the leading or trailing ends of the master patterns and by setting the first R or last R data samples of the modified master pattern equal to zero.
According to one method, a modified scanned pattern is generated by removing a predetermined number of leading or trailing data values of an original scanned pattern. Trailing or leading data values, respectively, are added to the modified scanned pattern with the added data values being copied from corresponding sequence positions of a corresponding master pattern. Alternatively, instead of explicitly removing leading or trailing data values, the leading or trailing data values may be effectively removed by adding data values to the opposite end of the scanned pattern and treating the modified scanned pattern as not including the xe2x80x9cremovedxe2x80x9d leading or trailing data values.
According to another method, a modified master pattern is generated in a similar manner except that added trailing or leading data values of the modified master pattern are set equal to data values copied from corresponding sequence positions of a scanned pattern.
According to another method, a modified master pattern is generated in a similar manner except that added trailing or leading data values of the modified master pattern are set equal to zero.
The above described modified patterns or pattern generation methods may be employed in currency identification systems to compensate for misalignment between scanned and master patterns.
According to another method, a scanned pattern comprising a number of data values is compared with one or more master patterns also comprising a number of data values. The scanned and master patterns represent analog variations in characteristic information retrieved from bills along corresponding segments. For example, the patterns may comprise 64 data values generated by sampling the output of a photodetector as a bill is moved relative to a scanhead, the output of the photodetector representing analog variation in the reflectance of light along a given segment of the bill. If none of the master patterns sufficiently match the scanned pattern, the scanned pattern may be modified and the modified scanned pattern compared to the master patterns. For example, data values #1 and #2 may be removed from the scanned pattern sequence, scanned patterns #3 and #4 may be made the first and second values in the modified sequence with subsequent data values modified accordingly. As a result of such a process, the original data values #63 and #64 now become modified data values #61 and #62. As a result of the above steps an incomplete modified pattern of data values #1-#62 is generated. According to one embodiment, modified data values #63 and #64 are generated by replicating data values #63 and #64 of the master patterns to which the modified scanned pattern is to be compared. If the modified patterns do not sufficiently match any of the master patterns, the modification process may be reiterated except that new scanned modified values #61-#64 are generated by replicating master pattern values #61-#64. This process is repeated until a sufficient match is found or until a predetermined number of modification iterations have occurred.
According to another embodiment, scanned patterns may be modified backwards instead of the forward modification described above.
According to another embodiment, master patterns may be modified instead of scanned patterns. According to this method, data values from scanned patterns are replicated into appropriate locations in modified master pattern sequences.
According to another embodiment, trailing or leading sequence positions of modified master patterns may be filled with zeros instead of replicated data values from a scanned pattern to which modified master patterns are to be compared.
According to another embodiment, modified master patterns with trailing or leading data values equal to zero are stored in a memory of an identification system along with corresponding unmodified master patterns, the master patterns and modified master patterns being stored before a bill under test is scanned by the identification system. When a bill under test is scanned by the identification system it is compared to one or more of the master patterns. If the identity of the bill can not be determined based on this comparison, the scanned pattern is compared with one or more of the modified master patterns. This process can be repeated, with the scanned pattern being compared to multiply modified master patterns if necessary.
According to another embodiment, a currency evaluation device is provided that is able to discriminate among bills of different denominations from two or more currency systems. In one embodiment, such a device is provided that is able to discriminate among both Canadian and German bills of different denominations. In one embodiment, such a device utilizes three scanheads when scanning Canadian bills and a single scanhead when scanning German bills. The device is able to accept faced Canadian and German bills fed in either the forward or reverse directions. According to one embodiment, the operator of the device pre-declares whether Canadian or German bills are to be discriminated. According to one embodiment the measured length of the narrow dimension of German bills is utilized in discriminating German bills. To accommodate for possible lateral shifting of bills relative to the scanhead, multiple German master patterns associated with laterally displaced scans are stored for some denominations. To accommodate for possible lateral shifting of bills relative to the scanheads, multiple Canadian patterns associated with laterally displaced scans are generated and averaged in generated stored Canadian master patterns. To compensate for problems associated with triggering scanning relative to the edge of a bill, multiple patterns are stored for both Canadian and German bills associated with both leading and lagging printed indicia.
In accordance with another embodiment of the present invention, a correlation technique is utilized whereby a scanned pattern generated from the green side of a test bill is correlated against stored green-side master patterns. If as a result of the green-side correlation, the denomination of the test bill can not be called, a scanned pattern generated from the black side of the test bill is correlated against stored black-side master patterns. More particularly, if the green-side correlation results in an indication that the test bill is a $20, $50, or $100 bill but not with sufficiently high certainty so as to permit calling the denomination of the test bill, then the black-side scanned pattern is correlated against one or more black-side master patterns, provided the best call green-side correlation number is greater than a predetermined threshold.
According to one embodiment, documents, including currency bills, are discriminated by comparing a scanned pattern retrieved from a first side of a test document with one or more stored master patterns retrieved from a first side of one or more genuine documents and comparing a scanned pattern retrieved from a second side of a test document with one or more stored master patterns retrieved from a second side of one or more genuine documents.
According to one embodiment a currency discriminator is provided that counts and discriminates bills as they pass a discriminating unit and that flags an unidentified bill or one having a predetermined characteristic, for example a bill having a specified orientation, by transferring the flagged bill to a location where it can be conveniently examined by an operator and then suspending the operation of the discriminator. The operator may then examine the bill and determine whether the bill is acceptable or not. Denomination selection elements such as keys are provided to enable the operator with the depression of a single button to indicate the denomination of an unidentified but acceptable bill, to cause the value of the bill to be reflected in any appropriate counters, and to cause the discriminator to resume operation. A continuation selection element is also provided to enable the operator to cause the discriminator to resume operation without adversely affecting any counters when an unidentified bill is determined to be unacceptable.
According to one embodiment of the present invention, a discriminator is provided with a single output receptacle in which all bills are stacked after they pass by the discriminating unit. When an unidentified bill is detected, the discriminator halts operation with the unidentified bill positioned at a predetermined location within the stack such as at the top or back of the stack of bills in the output receptacle or at a predetermined position just prior to the stack. The bill may then be conveniently examined by the operator.
According to another embodiment of the present invention, a discriminator is provided with an examining station where unidentified bills are transferred before the discriminator halts operation. Upon determination that a bill is acceptable, the bill may then be transferred to the output receptacle in a single output receptacle discriminator or to an output receptacle associated with the denomination or other characteristic of the bill in a multi-output receptacle discriminator. Additionally, a reject receptacle may be provided for receiving bills which are determined to be unacceptable.
In one embodiment, a discriminator is provided with two or more output receptacles. All flagged bills are delivered to a separate output receptacle while the discriminator continues to process any remaining bills. Alternatively, bills that are positively determined to be suspect bills may be delivered to one output receptacle, all other flagged bills may be delivered to a second output receptacle, and all unflagged and identified bills may be delivered to one or more additional output receptacles. In another embodiment, suspect bills are routed to a separate output receptacle while all other bills are routed to one or more additional output receptacles.
The discriminator, in another embodiment is designed to suspend operation upon encountering one or more types of flagged bills. For example, the discriminator may halt operation when a no call bill is detected but not when a suspect bill is detected, e.g., when suspect bills are routed to an output receptacle separate from the output receptacle or receptacles to which other bills are routed. According to another embodiment, the discriminator does not suspend its operation upon detecting a flagged bill but rather continues processing any remaining bills, e.g., when flagged bills are routed to one or more output receptacles separate from the output receptacle or receptacles to which non-flagged bills are delivered.
According to one embodiment, the value of any flagged bill such as a no call is reconciled on-the-fly, that is, at the time such bill is encountered. According to one such embodiment, the discriminator suspends operation until the value of the flagged bill is reconciled.
According to another embodiment, the value of any flagged bills is reconciled after all bills have been processed. Alternatively, the reconciliation process may begin before all bills have been processed but without suspending the processing of the remaining bills.
According to one embodiment, denomination indicating means are provided to permit the operator to indicate the value of a flagged bill such as a no call. Examples of denomination indicating means include, for example, denomination selection elements such as keys, buttons, switches, lights, and displayed keys, denominations, or messages. Such elements may be selected by, for example, pressing an appropriate one of such elements or using scroll keys. The selection of a denomination may cause that denomination to be indicated to the discriminator or, alternatively, a denomination may first have to be selected and then indicated to the discriminator by selecting an accept, yes, or enter key.
According to one embodiment, prompting means are provided whereby the discriminator is able to suggest a denomination to the operator of the discriminator in connection with a flagged bill such as call. Examples of criteria used in prompting a denomination to the operator in connection with a flagged bill include suggesting a denomination or a sequence of denominations based on a default basis, random basis, user-defined basis, manufacturer defined basis, last bill information, last no call information, last called denomination information, historical information, comparison of scanned and reference information such as correlation information. Means for prompting a denomination may include, for example, displaying a message, highlighting or illuminating a denomination selection or indicating element or associated light.
According to another embodiment of the present invention, a discriminator discriminates a stack of bills and flags bills having a given forward/reverse orientation. Accordingly, when a stack of bills predominately oriented in the forward or reverse direction is discriminated by the discriminator, any bills oriented in the opposite forward/reverse direction may be flagged. Any flagged bills may either be removed without replacement or re-oriented in the appropriate forward or reverse direction. As a result, a stack of bills may be generated in which all bills have the same forward/reverse orientation. Alternatively, in a multi-output receptacle discriminator, instead of flagging bills based on their forward/reverse orientation, bills having a forward orientation may be routed to one output receptacle and those having a reverse orientation may be routed to another output receptacle.
Likewise a discriminator may flag or sort bills based on their face orientation, that is face up or face down, or bills not belonging to a given denomination. Furthermore, the above criteria may be combined in various operating modes of the discriminator.
In one embodiment, the discriminator optically scans an area of a bill and generates a scanned pattern from optical reflectance samples. A scanned pattern is compared with a plurality of master patterns associated with genuine bills of different denominations. Furthermore, the discriminator may store master patterns associated with both forward and reverse scans and/or both top surface and bottom surface scans of genuine bills.
In one embodiment, a bill is scanned for first and second characteristic information, utilizing the first characteristic information to determine the denomination of a scanned bill, and using the second characteristic information to verify the genuineness of the bill. More particularly, a currency evaluation device, according to the present invention, comprises detection circuitry for detecting first and second characteristic information from a scanned bill, a memory for storing sets of genuine first and second characteristic information for a plurality of denominations of genuine bills, and signal processing means for comparing the detected first and second characteristic information with the stored genuine first and second characteristic information. The signal processing means performs a first comparison whereby the detected first characteristic information is compared with the stored sets of genuine first characteristic information. This first comparison results in either an indication of the denomination of the scanned bill or an error. The results of the first comparison are used to streamline a second comparison between detected and stored second characteristic information. The second comparison compares the detected second characteristic information with stored genuine second characteristic information corresponding to the denomination indicated by the first comparison. The second comparison results in either an indication of the genuineness of the scanned bill or an error.
According to one embodiment of the present invention, a document to be authenticated is illuminated with ultraviolet light and the amount of ultraviolet light which is reflected off the document is measured. Based on the amount of ultraviolet light which is detected, the document is either authenticated or rejected. In the case of documents being authenticated relative to United States currency, a bill is rejected if a high level of reflected ultraviolet light is not detected.
In another embodiment, the above objectives are achieved by illuminating a document with ultraviolet light and measuring both the amount of reflected ultraviolet light and the amount of emitted visible light. Based on the amount of ultraviolet light detected and the amount of visible light detected, a document is either authenticated or rejected. In the case of documents being authenticated relative to United States currency, a bill is rejected if either a high level of reflected ultraviolet light is not detected or even a low level of visible light is detected.
As explained above, it is known that some counterfeit United States bills fluoresce, or emit visible light, when illuminated by ultraviolet light. As genuine United States currency does not fluoresce, the emission of visible light has been employed as a means of detecting counterfeit United States currency. However, it has been found that not all counterfeit United States bills fluoresce; and hence, such counterfeits will not be detected by the above described fluorescence test.
It has been found that genuine United States currency reflects a high level of ultraviolet light when illuminated by an ultraviolet light source. It has also been found that some counterfeit United States bills do not reflect a high level of ultraviolet light. Such counterfeit bills may or may not also fluoresce under ultraviolet light. The present invention employs an authentication test wherein the amount of reflected ultraviolet light is measured and a bill is rejected if it does not reflect a high amount of ultraviolet light. By employing such a test, counterfeit United States bills which do not reflect a high level of ultraviolet light may be properly rejected.
While not all counterfeit United States bills fail to reflect a high level of ultraviolet light and hence not all counterfeit United States bills will be detected using this test, the present invention provides an additional means for detecting counterfeit bills which might otherwise go undetected. Furthermore, the likelihood of a counterfeit United States bill going undetected may be further reduced by employing an alternative embodiment of the present invention wherein both the amount of reflected ultraviolet light and the amount of emitted visible light are measured. In such a system, a bill is rejected as counterfeit if either it fails to reflect a high level of ultraviolet light or it fluoresces.
The above described embodiments may be adapted to authenticate currencies from other countries and other types of documents such as food stamps and checks. For instance some genuine documents may be designed to reflect ultraviolet light only in certain locations and/or in a predetermined pattern. An alternative embodiment of the present invention may be designed to accept documents which exhibit similar characteristics while rejecting those which do not. Likewise, an alternative embodiment of the present invention may be employed to authenticate documents based on both their characteristics with respect to reflected ultraviolet light and their characteristics with respect to fluorescent emissions, e.g., detecting the amount, location, and/or pattern of fluorescent emissions.